1. Field of the Invention
As is known the height of magnetic tape moving during operation of a tape recording/playback device, such as a video tape recorder (VTR) or the like, is subject to fluctuation. Thus a plurality of tape guide members including flanges for limiting movement of the tape in the width direction thereof are included in a tape drive mechanism to stabilize tape motion.
2. Description of the Related Art
The present invention relates generally to a tape guide mechanism for use in such as video tape recorders (VTRs), and various types of rotary head tape devices.
Conventional structure of such tape guide arrangements will be described hereinbelow with reference to FIGS. 1-4 wherein like reference numerals will be used to describe like parts. In FIG. 3 a circular bearing 51 is disposed around a main shaft 31. Upper and lower sides of the shaft are respectively retained by upper and lower bearings 37, 38. At ends of the shaft 31 flanges 40, 41 are respectively provided.
Referring now to FIG. 1, generally, in such magnetic tape recording and/or reproducing apparatus utilizing such tape loading arrangements as described above, a pivotal arm 32 is moveably mounted on the base plate (not shown) for facilitating tape loading. Projecting from a distal end of the arm 32 a support shaft 31 is provided having a threaded end portion 31a.
At an upper side of the support shaft 31 a flange member 33 is provided having an enlarged circumferential ring portion 35 and a shaft section 34 projected from a lower side thereof. The threaded and portion 31a of the support shaft 31 is engaged with a threaded opening 34a provided through said flange member 33 and the shaft section 34 thereof.
A cylindrical roller guide 36 is disposed around said support shaft 31 to be held between a base of the support shaft 31 and the ring portion 35 of the flange 33 so as to be disposed coaxially with the support shaft 31 and to be rotatable relative thereto. The cylindrical roller guide 36 includes an outer tape contact surface 36a.
A cylindrical bearing pressing member 43 is disposed coaxially with the support shaft 31 between the support shaft 31 and the roller guide 36. The bearing pressing member meets the upper flange 40 at an upper side thereof and the upper bearing 37 at the lower side thereof.
The upper and lower sides of the support shaft 31 are respectively encircled by upper and lower bearings 37, 38. At upper and lower ends of the cylindrical roller guide 36 flanges 40, 41 are respectively provided retaining the upper and lower bearings 37, 38 therebetween. Fitting around a lower side of the support shaft 31 a flange spacer 44 is provided comprising a cylindrical spacer portion 44a and a flange ring portion 44b. Also, the flange spacer 44 is interposed between the lower edge of the lower flange 41 and the arm 32.
Further, a coil spring 45 is provided which is fitted around a base portion of the support shaft 31 between the arm 32 and the flange ring portion 44b of the flange spacer 44. The coil spring 45 pushes the flanges 40 and 41 in the upward direction and applies upward biasing pressure on the components of the tape guide mechanism engaged between the flange spacer and the flange 33. Further adjustment spacers 46, 47 may be normally provided in such a tape guide mechanism. The upper adjustment 46 spacer is positioned between a lower side of the bearing pressing member 45 and the upper bearing 37 while the lower adjustment spacer is positioned between an upper side of the lower flange 41 and the lower bearing 38.
As may be seen in FIG. 4, each of the shaft receiving portions 37, 38 includes an inner ring 62, and outer ring 63, a plurality of balls 64, ball support portions 65 and a sheild member 66. Further, in order that excessive frictional heat is not generated according to rotation of the balls 64, a lubricant such as grease (not shown) is generally disposed in the bearings 37, 38.
According to provision of such lubricant, high performance may be obtained with smooth operation even during high speed rotation of the tape guide.
However, according to such conventional tape guide structure, over prolonged use leakage of such grease or other lubricant may occur between the sheild 66 and the inner ring 62 and/or between the sheild 66 and the outer ring 63. In other words, the lubricant may be caused to move in the directions of the arrows as shown in FIG. 4 and the performance of the tape guide mechanism is degraded and it is possible that lubricant may be contacted to the tape surface, possibly damaging the magnetic tape.
Thus, movement of lubricant in the directions as indicated in arrows a of FIG. 2 and arrows b-d or FIG. 3 may occur. Thus it has been required to provide a tape guide member in which lubricated bearings and the like are disposed such that migration of lubricant from the bearing to a tape contact surface such as the surface 36a of the roller guide or the inner sides off the flanges 40, 41, cannot occur.